This invention relates to a system of connecting a wired telecommunication and a radio communication, wherein, more particularly, a portable telephone unit is provided with a radio transmitter and receiver and a base unit also having a transmitter and receiver is designed to be connected to a commercial telephone line. Such systems, however, suffer the disadvantage of being subject to interference from other radio systems employing the same frequency bands. Also, telephone systems employing radio transmission are subject to having unauthorized long distance calls placed through their base units by other portable stations.